title: Isoform-specific regulation of the inositol 1,4,5-trisphosphate receptor by O-linked glycosylation.
abstract: The inositol 1,4,5-trisphosphate receptor (InsP(3)R), an intracellular calcium channel, has three isoforms with >65% sequence homology, yet the isoforms differ in their function and regulation by post-translational modifications. We showed previously that InsP(3)R-1 is functionally modified by O-linked β-N-acetylglucosamine glycosylation (O-GlcNAcylation) (Rengifo, J., Gibson, C. J., Winkler, E., Collin, T., and Ehrlich, B. E. (2007) J. Neurosci. 27, 13813-13821). We now report the effect of O-GlcNAcylation on InsP(3)R-2 and InsP(3)R-3. Analysis of AR4-2J cells, a rat pancreatoma cell line expressing predominantly InsP(3)R-2, showed no detectable O-GlcNAcylation of InsP(3)R-2 and no significant functional changes despite the presence of the enzymes for addition (O-β-N-acetylglucosaminyltransferase) and removal (O-β-N-acetylglucosaminidase) of the monosaccharide. In contrast, InsP(3)R-3 in Mz-ChA-1 cells, a human cholangiocarcinoma cell line expressing predominantly InsP(3)R-3, was functionally modified by O-GlcNAcylation. Interestingly, the functional impact of O-GlcNAcylation on the InsP(3)R-3 channel was opposite the effect measured with InsP(3)R-1. Addition of O-GlcNAc by O-β-N-acetylglucosaminyltransferase increased InsP(3)R-3 single channel open probability. Incubation of Mz-ChA-1 cells in hyperglycemic medium caused an increase in the InsP(3)-dependent calcium release from the endoplasmic reticulum. The dynamic and inducible nature of O-GlcNAcylation and the InsP(3)R isoform specificity suggest that this form of modification of InsP(3)R and subsequent changes in intracellular calcium transients are important in physiological and pathophysiological processes.
authors.affiliation: Department of Pharmacology, Yale University, New Haven, Connecticut 06520-8066, USA.
authors.forename: Patricia
authors.initials: P
authors.lastname: Bimboese
authors.forename: Craig J
authors.initials: CJ
authors.lastname: Gibson
authors.forename: Stefan
authors.initials: S
authors.lastname: Schmidt
authors.forename: Wanqing
authors.initials: W
authors.lastname: Xiang
authors.forename: Barbara E
authors.initials: BE
authors.lastname: Ehrlich
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000502:physiology*; D045744:Cell Line, Tumor; D004721:Endoplasmic Reticulum / Q000235:genetics / Q000378:metabolism*; D006031:Glycosylation; D006801:Humans; D015544:Inositol 1,4,5-Trisphosphate / Q000235:genetics / Q000378:metabolism*; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D017351:N-Acetylglucosaminyltransferases / Q000235:genetics / Q000378:metabolism*; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D051381:Rats
chemical_list: D053496:Inositol 1,4,5-Trisphosphate Receptors; D020033:Protein Isoforms; D015544:Inositol 1,4,5-Trisphosphate; D017351:N-Acetylglucosaminyltransferases; C037649:N-acetyllactosaminide beta-1,6-N-acetylglucosaminyltransferase; D002118:Calcium